The most important Meta tag is "Description" tag followed by "Keyword" tag. It's because in rankings description tag plays a very important role so right and correct placement of keywords in description tag is of vital importance for optimization.

Most major search engines no longer use META tags to determine search engine placement. Rather they use content to determine search engine placement since the searchers are interested at what is on a page on not what the page says about itself. In addition to continent, other factors include semantical coding (using <hx> tags for headings, <p> for paragraphs, etc), text in links referring to your site; position of search terms in your page (how close to the top, etc), number of sites linking to your page and so forth. FWIW, when I removed the meta keywords tag from my site, I jumped up five spots. Now I hover between second and third place.

Both answers are good and I'll only add to them. Search Engines DO read META tags but like Kim Siever says you need specific "code" to "require" them to read the tags. Is it helpful? yes and no. This is where the Guru's answer comes in. Let's say your keyword meta tag includes the words: Jones, Market, Sandals as the top three keywords. Your content needs to reflect this. You can't just keep repeating these three words in the first 200 words of your content, you'll get booted from the search engine (and they now take this stuff very serious) so DON'T do this: jones, market, sandals, jones, market, sandals, etc. Instead, you want to use these three words in your first 200 words (in your first frame if your site uses frames - which I highly recommend you change ASAP) as many times as possible in PARAGRAPH form. Suzie Jones Sandal Market is Las Vegas' #1 market for special and unique sandals. Suzie Jones trademark Bare Etta sandals are number one in the Nevada Market and East Coast Market. etc etc etc. Some keys to add to to this are referral links (banners, text links, business directories, search engines, other sites, etc) REALLY help your ranking to. It's how the search engine "builds" it's data (the "spider" picks up the links and crawls their sites too). Also, dynamic (database) sites help your ranking because in database format, you content can change on every page with little or no effort and search engines crawl the data and rank higher on dynamic (changing pages) as well as the number of pages your site can have in the system which increases your overall referral sites as well. If you have other SEO questions or would like more clarity, please feel free to email me directly.

I would think that a "smart" search engine/spider will read the description and keyword meta tags, and "assume" that this is what the page is about, then check the page. If the content on the page matches the meta information, then it would get extra points. If not, then it might take away points for lying. I was able to boost our website (http://tmetrix.com/) to first page results for terms I used in meta tags AND content. -Frank